Coupling process

ABSTRACT

Process for coupling an alkane to either an alkane, alkene, aliphatic carboxylic acid, or aromatic hydrocarbon by effecting contacting thereof and a melt containing a multivalent metal halide in both its higher and lower valance state. In accordance with a preferred embodiment, the contacting is effected in the presence of an oxygen containing gas or the melt is previously contacted with an oxygen containing gas to produce the corresponding oxyhalide of the metal, whereby the reaction may be effected on a continuous basis.

This is a division of application Ser. No. 769,791, filed 10/23/68, nowU.S. Pat. No. 3,947,489.

This invention relates to a coupling process and more particularly tothe production of both saturated and olefinically unsaturated compoundsby a coupling reaction.

The production of olefinically unsaturated compounds by a couplingreaction is known in the art; however, in most processes the reactionrequires an unsaturated starting material which raises overall costs.Thus, for example, styrene, a valuable polymerization monomer, isproduced by reacting benzene with ethylene to produce ethyl benzenewhich is then dehydrogenated to styrene. As a further example, vinylacetate, another valuable polymerization monomer is produced bycombining acetylene with acetic acid.

Accordingly, an object of this invention is to provide a new andimproved coupling process.

Another object of this invention is to produce saturated andolefinically unsaturated compounds by a coupling reaction.

A further object of this invention is to provide a process for couplingtwo alkanes.

Still another object of this invention is to provide a process forproducing ethyl benzene.

A still further object of this invention is to provide a process forproducing styrene.

Yet another object of this invention is to provide a process forproducing vinyl acetate.

These and other objects of the invention should be more readily apparentfrom the following detailed description thereof when read with referenceto the accompanying drawings wherein:

The drawing is a simplified schematic flow diagram of an embodiment ofthe invention.

The objects of this invention are broadly accomplished by contacting analkane with either: another or identical alkane; an olefinicallyunsaturated compound; an aliphatic carboxylic acid; or an aromaticcompound, in the presence of a melt containing a multivalent metalhalide in both its higher and lower valence state. The contacting may beeffected in the presence of other reagents, as hereinafter described,with reference to preferred embodiments of the invention. As a result ofthe contacting, a compound is produced containing one portioncorresponding to the alkane, with the remainder of the compoundcorresponding to the other compound employed in the contacting step.

The melt contains a halide of a multivalent metal; i.e., a metal havingmore than one positive valence state, such as manganese, iron copper,cobalt and chromium, preferably a chloride or bromide of the metal, withthe copper chlorides and bromides, in particular the copper chlorides,being preferred. In the case of higher melting multivalent metalhalides, such as copper chlorides, a halide of a univalent metal; i.e.,a metal having only one positive valence state, which is nonvolatile andresistant to the action of oxygen under the process conditions is addedto the multivalent metal halide to form a molten salt mixture having areduced melting point. The univalent metal halides, the chlorides andbromides, particularly the chlorides, being preferred, are preferablyalkali metal halides, such as potassium and lithium chloride inparticular, but it is to be understood that other metal chlorides andmixtures thereof, such as the heavy metal halides of Groups I, II, IIIand IV of the Periodic Table; e.g., zinc, silver. and thallium chloride,may also be employed. The univalent metal halides are generally added inan amount sufficient to adjust the melting point of the molten saltmixture to a temperature of below about 500° F., and in the case of asalt mixture of copper chloride and potassiun chloride, the compositionof the melt ranges between about 20% and about 40%, preferably about30%, by weight, potassium chloride, with the remainder being copperchloride. It is to be understood, however, that in some cases thecatalyst melt may have a melting point higher than 500° F., provided thecatalyst remains in the form of the melt throughout the processingsteps. It is further to be understood that the melt may contain amixture of multivalent metal halides or other reaction promoters; e.g.,a known coupling catalyst, e.g., palladium salt such as palladiumchloride; i.e., 0.5-4.0 wt. %. It is also to be understood that in somecases the multivalent metal halide (s) may be maintained as a meltwithout the addition of a univalent metal halide.

The alkane, as hereinabove described, is contacted with either anotheror identical alkane, preferably a different alkane (isomers containingthe same number of carbon atoms are different alkanes), generally asalkane containing no more than about 9 carbon atoms, such as methane,ethane, propane, the various butanes and the like; an olefinicallyunsaturated compound, generally an alkane containing no more than about9 carbon atoms, such as ethylene, propylene, the various butenes, andthe like; an aliphatic carboxylic acid, generally an alkanoic acid,preferably containing no more than about 5 carbon atoms, such as aceticacid, propionic acid and the like; of an aromatic compound, generally inaromatic hydrocarbon, preferably mononuclear, such as benzene. The feedmay contain two or more of such compounds in which case the effluentcontains a mixture of products.

The process of the invention results in a coupling of the alkane to theother reactant to produce a combined compound. Thus, the coupling of thealkane with another or identical alkane results in the production of analkane and/or alkane, generally a mixture of alkane and alkenecontaining a number of carbon atoms corresponding to the total number ofcarbon atoms of the two alkane reactants; with an alkene results in theproduction of an alkane and/or alkene, generally a mixture of alkane andalkene containing a number of carbon atoms corresponding to the totalnumber of carbon atoms of the alkane and alkene; with an alkanoic acidresults in the production of an alkenyl ester of the acid; and with anaromatic hydrocarbon results in the production of an alkenyl and/oralkyl substituted derivative thereof. Thus, for example, the coupling ofethane in accordance with the invention with propane produces pentaneand/or pentene; with butylene produces hexane and/or hexene; withpropionic acid produces vinyl propionate; and with benzene producesstyrene and/or ethyl benzene. Similarly, the coupling of propane withbenzene produces cumene and/or propenyl benzene.

It has been found that contacting of the feed to be coupled with thehereinabove described melt results in a net production of hydrogenchloride and a depletion of the content of the higher valent metalchloride; i.e., cupric chloride, in the melt. Therefore, in accordancewith one preferred embodiment of the invention, the feed to be coupledis contacted with the melt, containing the multivalent metal halide inboth its higher and lower valence state, in the presence of anoxygen-containing gas, such as air. This procedure results inessentially no net production of hydrogen chloride and maintains thehigher valent metal halide content of the melt substantially constant.

As an alternative procedure to the hereinabove described preferredembodiment, the melt containing a mixture of a multivalent metal halidein both its higher and lower valence state may be initially contactedwith oxygen and the resulting product, containing the correspondingoxyhalide of the multivalent metal, is then contacted with the feed tobe coupled. This procedure also results in essentially no net productionof hydrogen chloride and a substantially constant content of cupricchloride and is of greater commercial value in that oxygen does notcontact the feed, thereby decreasing any losses which may result fromcombustion of the feedstock.

As a further embodiment, the feed to be coupled is contacted with themelt, containing the multivalent metal halide in both its higher andlower valence state, in the presence of a free halogen containing gas,correspondng to the halide of the multivalent metal. This procedurealthough maintaining essentially no net loss of cupric chloride, resultsin a net production of hydrogen chloride and consequently is lesspreferred than the hereinabove described preferred embodiment. It is tobe understood that similarly to the preferred embodiment, the melt maybe contacted with the free halogen containing gas separately from thecoupling step to replenish the cupric chloride content of the melt.

As a further alternative embodiment, the hydrogen chloride generated inthe coupling reaction, may be recovered from the effluent and employedalong with an oxygen-containing gas to contact the cupric chloridedepleted melt to regenetate cupric chloride for the subsequent couplingstep. This procedure is also less preferred, but may be employed withinthe scope of the invention.

The various contacting steps including contacting of the melt withoxygen, chlorine, or hydrogen chloride, as hereinabove described aregenerally effected at temperatures from about 500° to about 1,200° F.and pressures from about 1 to about 30 atmospheres. The contacting ispreferably effected in a countercurrent fashion, with the feed as acontinuous vapor phase, at residence times between about 1 and about 100seconds. The choice of optimum reaction conditions varies with theparticular reactants and desired rection products, and, therefore, thehereinabove described conditions are illustrative of the invention andthe scope thereof is not to be limited thereby. Thus, for example, inthe coupling of ethane to benzene, ethyl benzene is generally producedat temperatures from about 500° F. to about 1,000° F. and styrene attemperatures from about 700° F. to about 1,200° F., with a mixture ofethyl benzene and styrene being produced at the overlapping portions ofthe temperature range; i.e., from about 700° F. to about 1,000° F. It isfurther to be understood that by-products are also produced during thereaction and, therefore, the reaction conditions are controlled toreduce such production. The separation of the resulting by-products inorder to recover the desired product may be effected by a wide varietyof well-known procedures and, therefore, no detailed explanation thereofis deemed necessary.

It should be further apparent from the hereinabove description of theinvention that the melt containing the multivalent metal halideparticipates in the reaction sequence and accordingly does not behavesolely as a catalyst. Therefore, the multivalent metal halides must bepresent in an amount sufficient to meet reaction requirements and ingeneral the melt composition should contain at least 3%, by weight, ofthe higher valent halide, although greater amounts are preferred. Insome cases, the addition of chlorine may be required in order tomaintain the necessary quantity of cupric chloride.

The melt in addition to functioning as a reactant and/or catalyst is atemperature regulator. Thus, the circulating melt has a high heatabsorption capacity thereby preventing runaway reaction during theexothermic coupling and oxygen contacting steps. The absorbed heat ofreaction may be employed to heat the various reactants to rectiontemperature. Alternatively, or in addition to such an expedient, themelt may be contacted with an inert gas coolant to remove any additionalheat of reaction, with the inert gas being subsequently cooled andre-employed for removing heat from the melt. It should be apparent,however, that if additional heat is required such heat may be suppliedfrom an external source.

The invention will now be further described with reference to anembodiment thereof illustrated in the accompanying drawing. It is to beunderstood, however, that the scope of the invention is not to belimited thereby.

Referring now to the drawing, an oxygen-containing gas in line 10, suchas air, is introduced into a reactor 11, containing suitable packing 12or other liquid-vapor contacting devices. A melt containing amultivalent metal halide in both its higher and lower valence state,such as a mixture of cupric and cuprous chloride, is introduced intoreactor 11 through line 13 in the form of a melt and countercurrentlycontacts the ascending oxygen-containing gas. The melt may furthercontain an alkali metal chloride, such as potassium chloride. As aresult of such contact, a portion of the cuprous chloride isexothermically converted to copper oxychloride.

An oxygen depleted gas in the top of the reactor 11 is contacted with aquench liquid introduced through line 14, resulting in condensation ofvaporized melt and vaporization of quench liquor. The vaporized quenchliquid and oxygen-depleted gas is withdrawn from reactor 11 through line15 and introduced into a cyclone separator 16 to effect separation ofentrained catalyst. The separated catalyst is withdrawn from separator16 through line 17 and returned to the reactor 11. The combinedoxygen-depleted gas-vaporized quench liquid is withdrawn from separator16 through line 18, passed through condenser 19 to effect condensationof the quench liquid and the vapor-liquid mixture introduced into aseparator 21. The quench liquid is withdrawn from separator 21 in line14 and recycled to the reactor 11. The oxygen-depleted gas is withdrawnfrom separator 21 through line 22 and passed to waste.

The melt-containing a mixture of cuprous chloride, cupric chloride andcopper oxychloride is withdrawn from reactor 11 through line 31 andintroduced into the top of a coupling reactor 32, containing suitablepacking 33 or other gas-liquid contacting devices. A feed to be coupled,such as ethane and acetic acid, is introduced into the bottom of vessel32 through line 34 and countercurrently contacts the descending melt toeffect coupling of the feed. The melt withdrawn from the bottom ofvessel 32 through line 13 is recycled to reactor 11.

A gaseous effluent containing vinyl acetate and by-products, iscontacted in the top of vessel 22 with a quench liquid introducedthrough line 35, resulting in condensation of vaporized catalyst meltand vaporization of the quench liquid. The vaporized quench liquid andeffluent is withdrawn from vessel 32 through line 36 and introduced intoa cyclone separator 37 to effect removal of entrained catalyst. Theseparated catalyst is withdrawn from separator 37 through line 38 andrecycled to the vessel 32. The vaporized quench liquid and gaseouseffluent are withdrawn from separator 37 through line 39, passed throughcondenser 41 to effect condensation and cooling of the quench liquid andthe gas-liquid mixture is introduced into a separator 42. The now cooledquench liquid is withdrawn from separator 42 through line 35 andrecycled to the reactor 32. The effluent is withdrawn from separator 42through line 43 and passed to separation and recovery.

It is to be understood that numerous variations of the hereinabovedescribed processing sequence are possible within the spirit and scopeof the invention. Thus, for example, the coupling reaction may beeffected in a single reactor having two separate zones, one for theintroduction of an oxygen-containing gas for contact with the melt andthe other for contacting the resulting oxygenated melt with the feed tobe coupled. Alternatively, as hereinabove described, the melt containingthe multivalent metal halide in both its higher and lower valence state,may be contacted with a mixture of an oxygen-containing gas and a feedto be coupled. Similarly, a halogen containing gas, such as chlorine,may be employed instead of an oxygen-containing gas in which case ashereinabove described, there is a net production of hydrogen chloride.These and other modifications should be apparent to those skilled in theart from the teachings contained herein.

The invention is further illustrated by the following examples but thescope of the invention is not to be limited thereby.

EXAMPLE I

Ethane and acetic acid are coupled by countercurrently contacting anethane-acetic acid mixture with a copper chloride containing melt whichhas previously been contacted with air, under the following conditions:

    ______________________________________                                        Reaction Temperature    395° C.                                        Reaction Pressure       1 atm                                                 Molten Salt                                                                    KCl                    30 wt %                                                CuCl                   55 wt %                                                CuCl.sub.2             15 wt %                                               Residence Time          11 seconds                                            Duration of Test        1.5 hours                                             Gas Hourly Space Velocity, GHSV                                                                       75                                                    Feed Rate, gm-mole/hr                                                          C.sub.2 H.sub.6        0.22                                                   Acetic Acid            0.10                                                  Percent Vinyl acetate in liquid                                               product                 4.5%                                                  ______________________________________                                    

EXAMPLE II

Ethane and benzene are coupled under the following conditions bycountercurrently contacting an ethane-benzene mixture with a copperchloride containing melt which has previously been contacted with air.

    ______________________________________                                        Reaction Temperature    355° C.                                        Reaction Pressure       1 atm                                                 Molten Salt                                                                   KCl                     30 wt %                                               CuCl                    40 wt %                                               CuCl.sub.2              30 wt %                                               Residence Time          9.0 sec.                                              Duration of Test        3 hours                                               Gas Hourly Space Velocity, GHSV                                                                       83                                                    Feed Rate, gm-mole/hr                                                          Ethane                 0.67                                                   Benzene                0.39                                                  Ethane Conversion       5.0%                                                  ______________________________________                                    

The reaction product contains mainly ethyl benzene and some styrene.

EXAMPLE III

The procedure of Example II is repeated except that the temperature israised to 483° C.

The reaction product contains mainly styrene and some ethyl benzene.

EXAMPLE IV

Isobutane is coupled to n-butane by contacting a mixture thereof with acopper chloride melt under the following conditions:

    ______________________________________                                        Reaction Temperature    386° C.                                        Reaction Pressure       1 atm                                                 Molten Salt                                                                    KCl                    30 wt %                                                CuCl                   45 wt %                                                CuCl.sub.2             25 wt %                                               Residence Time          10 sec.                                               Duration of Test        3 hours                                               Gas Hourly Space Velocity, GHSV                                                                       79                                                    Feed Rate, gm-mole/hr                                                          Isobutane              0.23                                                   n-Butane               0.23                                                  Isobutane Conversion    16%                                                   ______________________________________                                    

The reaction product contains C₈ alkanes and alkenes.

EXAMPLE V

The procedure of Example IV is repeated except that the feed is amixture of pentane and propylene.

The reaction product is a mixture of C₈ alkanes and alkenes.

EXAMPLE VI

The procedure of Example I is repeated except that the melt has thefollowing composition:

    ______________________________________                                        FeCl.sub.2          58 wt %                                                   FeCl.sub.3           8 wt %                                                   KCl                 34 wt %                                                   ______________________________________                                    

The reaction product contains vinyl acetate.

EXAMPLE VII

The procedure of Example III is repeated except that the melt has thefollowing composition:

    ______________________________________                                        MnCl.sub.2           3 wt %                                                   MnCl.sub.4          80 wt %                                                   KCl                 17 wt %                                                   ______________________________________                                    

The reaction product contains mainly styrene and some ethyl benzene.

EXAMPLE VIII

The procedure of Example II is repeated except that the melt has thefollowing composition:

    ______________________________________                                        CoCl.sub.2          14 wt %                                                   CoCl.sub.3          49 wt %                                                   KCl                 37 wt %                                                   ______________________________________                                    

The reaction product contains mainly ethyl benzene and some styrene.

EXAMPLE IX

The procedure of Example IV is repeated except that the temperature is483° C. and the melt has the following composition:

    ______________________________________                                        CrCl.sub.2           5 wt %                                                   CrCl.sub.3          74 wt %                                                   KCl                 21 wt %                                                   ______________________________________                                    

The reaction product contains C₈ alkanes and alkenes.

EXAMPLE X

The procedure of Example II is repeated except that the feed containspropane and benzene.

The reaction product contains cumene.

EXAMPLE XI

The procedure of Example I is repeated except that the melt includes apalladium chloride promoter. The melt has the following composition.

    ______________________________________                                        KCl                 27 wt %                                                   CuCl                55 wt %                                                   CuCl.sub.2          15 wt %                                                   PdCl.sub.2           3 wt %                                                   ______________________________________                                    

The reaction product contains vinyl acetate.

The hereinabove examples are also repeated with bromides and iodides ofthe multivalent metals with similar results.

The process is extremely advantageous in that olefinically unsaturatedcompounds may be produced in a single reactor. As a further advantage,valuable products such as styrene, ethyl benzene, and vinyl acetate maybe produced in a single reactor without using an unsaturated compound asa starting material. These and other advantages of the invention wouldbe readily apparent to those skilled in the art.

Numerous modifications and variations in the present invention arepossible in light of the above teachings and, therefore, it is to beunderstood that the invention may be practiced otherwise than asparticularly described.

What is claimed is:
 1. A process for coupling an alkane with at leastone member selected from the group consisting of different alkanes,having a number of carbon atoms different than the number of carbonatoms of said alkane, alkenes, and aromatic hydrocarbons,comprising:contacting the alkane and said member, both in the vaporphase, with a molten mixture comprising a multivalent metal halide inboth its higher and lower valence state, said multivalent metal halidebeing selected from the group consisting of the chlorides, iodides andbromides of copper, manganese, iron, cobalt and chromium, saidcontacting being effected at a temperature from about 500° to about1,200° F to produce a reaction effluent containing a coupled compoundcontaining a number of carbon atoms corresponding to the total number ofcarbon atoms in said alkane and said member, said coupled compound whensaid member is said different alkane or said alkene being selected fromthe group consisting of alkanes, alkenes and mixtures thereof, and saidcoupled compound when said member is said aromatic hydrocarbon beingselected from the group consisting of alkyl and alkenyl substitutedderivatives of said aromatic hydrocarbon and mixtures thereof.
 2. Theprocess as defined in claim 1 wherein the multivalent metal halide is achloride.
 3. The process as defined in claim 2 wherein the moltenmixture includes as a melting point depressant a chloride of an alkalimetal or a heavy metal of Groups I, II, III or IV of the Periodic Table.4. The process as defined in claim 2 wherein said alkane has no morethan 9 carbon atoms and said member is benzene.
 5. The process asdefined in claim 4 wherein the multivalent metal chloride is copperchloride.
 6. The process as defined in claim 5 wherein said alkane isethane and said member is benzene, said coupled compound being selectedfrom the group consisting of ethyl benzene, styrene and mixturesthereof.
 7. The process as defined in claim 6 wherein said moltenmixture comprises cuprous chloride, cupric chloride and potassiumchloride.
 8. A process for coupling an alkane having no more than 9carbon atoms with at least one member selected from the group consistingof different alkanes having a number of carbon atoms different than saidalkane and no more than 9 carbon atoms, alkenes having no more than 9carbon atoms, and benzene, comprising:contacting oxygen, the alkane andsaid member, all in the vapor phase, with a molten mixture comprising amultivalent metal chloride in both its higher and lower valence state,said multivalent metal chloride being selected from the group consistingof the chlorides of copper, manganese, iron, cobalt and chromium, saidcontacting being effected at a temperature from about 500° F to about1,200° F to produce a coupled compound containing a number of carbonatoms corresponding to the total number of carbon atoms in said alkaneand said member, said coupled compound when said member is saiddifferent alkane or said alkene being selected from the group consistingof alkanes, alkenes and mixtures thereof, and said coupled compound whensaid member is said aromatic hydrocarbon being selected from the groupconsisting of alkyl and alkenyl substituted derivatives of said aromatichydrocarbon and mixtures thereof.
 9. The process as defined in claim 8wherein the molten mixture includes as a melting point depressant achloride of an alkali metal or a heavy metal of Groups I, II, III or IVof the Periodic Table.
 10. The process as defined in claim 9 wherein themultivalent metal chloride is copper chloride.
 11. The process asdefined in claim 10 wherein said molten mixture comprises cuprouschloride, cupric chloride and potassium chloride.
 12. The process asdefined in claim 10 wherein said molten mixture further comprises apalladium salt in an amount from about 0.5% to about 4.0%, by weight, ofthe molten mixture.
 13. The process as defined in claim 12 wherein thepalladium salt is palladium chloride.
 14. The process as defined inclaim 19 wherein said alkane is ethane, said member is benzene and saidcoupled compound is selected from the group consisting of ethyl benzene,styrene and mixtures thereof.
 15. A process for coupling an alkanehaving no more than 9 carbon atoms with at lease one member selectedfrom the group consisting of different alkanes having a number of carbonatoms different than said alkane and no more than 9 carbon atoms,alkenes having no more than 9 carbon atoms, and benzene,comprising:contacting the alkane and said member, both in the vaporphase, with a molten mixture comprising a multivalent metal chloride inboth its higher and lower valence state and the oxychloride of saidmetal, said multivalent metal chloride and oxychloride being selectedfrom the group consisting of the chlorides and oxychlorides of copper,manganese, iron cobalt and chromium, said contacting being effected at atemperature from about 500° F to about 1,200° F to produce a coupledcompound containing a number of carbon atoms corresponding to the totalnumber of carbon atoms in said alkane and said member, said coupledcompound when said member is said different alkane or said alkene beingselected from the group consisting of alkanes, alkenes and mixturesthereof, and said coupled compound when said member is said aromatichydrocarbon being selected from the group consisting of alkyl andalkenyl substituted derivatives of said aromatic hydrocarbon andmixtures thereof.
 16. The process as defined in claim 15 wherein themolten mixture includes as a melting point depressant a chloride of analkali metal or a heavy metal of Groups I, II, III or IV of the PeriodicTable.
 17. The process as defined in claim 16 wherein the multivalentmetal chloride and oxychloride is copper chloride and copperoxychloride.
 18. The process as defined in claim 15 wherein said moltenmixture comprises cuprous chloride, cupric chloride, copper oxychlorideand postassium chloride.
 19. The process as defined in claim 17 whereinsaid alkane is ethane, said member is benzene and said coupled compoundis selected from the group consisting of ethyl benzene, styrene, andmixtures thereof.